Those counties with phosphate deposits are shown in Figure 3. Hills- 

 borough, Manatee, and Sarasota Counties hold phosphate deposits ohat are 

 likely to be mined in the future. Demands for mining sites and increased 

 urbanization are sure to be competitive. Mining will probably continue to 

 affect water quality by contaminating freshwater runoff. The synthesis paper 

 on mineral resources gives more information on mining forecasts in Southwest 

 Florida. 



The percentage change of land in farms for 1950, 1959, and 1969 are given 

 in Figure 4. Although agriculture is important to the region's economy, it is 

 losing to urban development in the coastal counties. The loss of agricultural 

 lands has been compensated for by intensifying productivity. This trend is 

 expected to continue into the future. Agriculture still has a major influence 

 on water quality and quantity throughout Florida because 

 for irrigation. Agricultural trends in Southwest Florida 

 in the chapter on agriculture in this report. 



it uses so much water 

 are further described 



CLASS I DRINKING WATER 



FEDERAL AND STATE STANDARDS 



The Federal Safe Drinking Water Act of 1974 (P.L. 93-523) instructs the 

 U.S. Environmental Protection Agency to establish regulations for safe drink- 

 ing water. The State of Florida has taken the Federal guidelines and incor- 

 porated them into the Class I water quality criteria discussed earlier in this 

 report. These standards establish the minimum criteria required for safe 

 drinking water from ground (Class IB) and surface (Class lA) water supplies. 

 A Class IB underground source of drinking water is an aquifer or part of an 

 aquifer that supplies water suitable for drinking and contains fewer than 

 10,000 mg/1 of total dissolved solids (most ground water in Florida has less 

 than 250 mg/1 of dissolved solids). About 92% of the State's residents depend 

 upon aquifers for a source of potable water. In Southwest Florida, citizens 

 are largely dependent on the Floridian aquifer (the State's largest) and 

 shallow sand-and-gravel aquifers. Part C of the Federal Safe Drinking Water 

 Act (P.L. 92-523) establishes guidelines for State programs to protect under- 

 ground drinking water sources. Regulations are designed to protect present 

 and future supplies. 



The potential pollution sources that most threaten the State's 

 groundwater are discharges of municipal and industrial wastes. Even 

 runoff sometimes is contaminated by waste disposal practices 



potable 



surface 



(Figure 5). 



To protect Florida's valuable groundwater resources, the State has 

 enacted a series of regulatory programs. The most important one is an under 

 ground injection control. This program is designed to ensure that injected 



fluids from Florida's 6,858 injection 

 zone and do not migrate into drinking 

 the major types of subsurface aquifers 

 five classes of underground injection 

 given in Figure 6. 



wells stay in the intended injection 

 water supplies. An annotated list of 

 and the general characteristics of the 

 wells regulated within the State are 



275 



